The present invention relates to a partition system for providing speech privacy in open plan office spaces and more particularly to such a system providing a speech masking acoustic field.
While speech privacy can be obtained by effecting isolation i.e. the providing of barriers between different conversations, the extent to which such isolation can be created in open plan office spaces is highly limited. It has long been recognized, however, that effective speech privacy is determined not only by the degree of isolation but also by the level of unobtrusive background noise. To this end, various schemes have been developed for generating broadband acoustic fields which unobtrusively raise the background noise level and therefore increase effective speech privacy without interfering with productivity or being an annoyance. The most successful systems of this type have been those which employ multiple, independently driven speaker systems mounted above dropped ceilings over the office space. The plenum, that is, the space between the dropped ceiling and the structural ceiling, acts as a chamber which helps to distribute the sound energy from each of the speakers and thereby minimizes the perception of discrete sound sources. In other words, the masking sound is relatively uniformly distributed and does not appear to be coming from any particular point as a person moves through the office space. Such a system is described in U.S. Letters Pat. No. 4,059,726 issued on Nov. 22, 1977 to Bill G. Watters, Michael Nacey, and Thomas R. Horrall.
Plenum-mounted speaker systems, while highly effective, are initially expensive to install and are very difficult to move or modify as office requirements change. Since the transmission acoustic properties of the dropped ceiling may be markedly different at the location of light fixtures and air conditioning outlets, it may be necessary to employ individually-fitted acoustic blankets around such fixtures. A further problem is that some codes have required that all the wiring for such speaker systems be installed in conduit. The cost of this conduit wiring may equal the basic cost of the system itself.
Various attempts have been made to provide furniture-mounted masking noise sources but these have been largely unsuccessful in that the individual sound sources were easily locatable by ear as well as visually. The ability to perceive the location of the sound sources was typically due to the non-uniformity of the acoustic field created, as well as to the typical visually obvious mounting of the sound generator. Attempts to minimize the non-uniformity of the field, e.g. by directing the sound upward so that it was reflected back off the ceilings, were largely ineffectual. Consciousness of the presence of the sound sources generally made their existence annoying to office workers in the supposedly improved office space and the usual response was to make innapropriate adjustments to the sources or even to completely turn them off.
Among the several objects of the present invention are the provision of a partition system for open plan office spaces which provides effective speech privacy; the provision of such a system which employs the generation of a broadband masking sound field; the provision of such a system in which the sound field is perceived as uniform; the provision of such a system in which the sources of the sound field are not readily locatable; the provision of such a system which provides both isolation and a masking sound field; the provision of such a system which is easily installed; the provision of such a system which is highly reliable; and which is of relatively simple and inexpensive construction. Other objects and features will be in part apparent and in part pointed out hereinafter.